Solve for $p$ : $13 + p = 19$
Solution: Subtract $13$ from both sides: $ \begin{eqnarray} \\ 13 + p &=& 19 \\ \\ {-13} && {-13} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{13 + p} &\hphantom{=}& \hphantom{19} \\ p &=& 19 {- 13} \\ \end{eqnarray} $ Simplify. $ p = 6$